Modern competition and mass recreation size swimming pools are provided with perimeter water circulating systems, such as illustrated in U.S. Pat. Nos. 4,179,761; 4,316,571 and 4,400,834. These systems include a pressurized perimeter tube to supply water to the pool on a continuous flow basis. Associated with this tube is a gutter adapted to conduct water from the pool to filtration systems from which the water is then returned to the perimeter tube.
Pool sanitation is a major concern of pool operators and is regulated by state health departments. For instance, it has been long recognized that accumulations of body hair and hair oils, and other forms of floating pool contaminants and debris should be removed from the pool on a regular and systematic basis in order to maintain a safe environment for swimmers. However, if a pool gutter is flooded due to a surge of water caused by a large influx of swimmers, accumulated contaminants and debris in the gutter will be flushed back into the pool. To prevent gutter flooding many state health departments require that the surge storage capacity of pool gutters be at least one gallon per square foot of pool surface area. In addtion, surge tanks adjacent to the pool with connections to the gutters are also required by state regulations. Subsequent to the promulgation of these regulations, pool surface skimming and surge control devices have been developed which have eliminated the need for surge tanks. These devices have generally been accepted by state health departments in lieu of surge tanks because they provide a more efficient sanitary gutter system at substantial savings over the surge tank system.
Skimming devices serve two functions. The first is to provide pool surface skimming which effectively removes floating contaminants and debris from the pool. The second is to provide state required in-pool surge capacity. Examples of prior art skimming devices intended to serve these two functions are disclosed in the following U.S. Pat. Nos.: 3,668,713; 3,918,107; 4,112,526; 4,146,937; 4,173,799; and 4,494,257.
In theory the skimmers operate by accepting a steady flow of water from the pool surface when the pool is quiescent, but which close responsive to a sudden surge of water. When the skimmers close, water can only reach the gutter by entering over the gutter rim. Since the gutter rim is several inches higher than the skimmer weir, properly designed, the gutter has adequate capacity and time to accept the surge without flooding. In practice, however, it is a general observation that most prior art skimmers are erratic in their ability to remain closed when a local surge occurs. Thus, for example, U.S. Pat. Nos. 4,173,799 and 4,146,937 disclose skimmers which will fluctuate when local surging occurs. U.S. Pat. No. 3,668,713 will fluctuate when local surging occurs and will also fail completely when the water in the gutter reaches a certain critical level.